Nickel metal hydride (NiMH) 14.4V 2500 mAh battery with more than 500 recharging cycles. Even though this kind of battery has no memory effect, it will self-discharge over the time. Customer needs to charge the battery fully before using the CleanMate QQ-2. If QQ-2 will not be used for long period of time, please fully charge battery and remove it from battery compartment to prevent discharging. QQ-2 NiMH battery will lasts for hundreds of cleaning cycles. However, the battery may require more frequent recharging after some period of time. Frequent use and regular re-charging battery along with cleaning of brush will make QQ-2 battery’s life last longer.